1. Field of Invention
This invention relates generally to semiconductor light-emitting devices, and more specifically to electrical contacts for semiconductor light-emitting devices.
2. Description of Related Art
Semiconductor light-emitting devices such as light-emitting diodes (LEDs) provide efficient sources of light and are more robust than incandescent light bulbs and fluorescent tubes. Advancements in LED technology and processing have facilitated the use of such devices as replacements for traditional lighting sources in commercial and residential lighting applications, for example. Efficiency and reliability are thus important aspects of LEDs used in lighting applications. Additionally demands for increased light output from LEDs are growing resulting in higher operating currents.
It is common to fabricate LEDs with both n-type and p-type contacts on the same side of the semiconductor die, such that light may be emitted from a light output surface unimpeded by electrical contacts. In such cases electrical contact to at least one of the layers may extend through the other layers of the die, thus reducing the light generating area within the LED. Semiconductor materials used for n-type and p-type regions of semiconductor LEDs generally have low carrier mobility. Consequently a plurality of contacts are commonly used to supply current to an inner semiconductor layer of the LED such that the current spreads out across the layer, thus causing substantially uniform generation of light in the LED. However, employing a plurality of contacts may reduce the light generating area of the LED and thus in general, electrical contact design in LEDs involves a trade-off between current spreading and usable light generating area remaining once the contacts have been formed.
There remains a need for improved processes for forming electrical contacts for semiconductor LEDs.